Process for removing metals from crude oils and then hydrodesulfurizing the crude oil



Nov. 27, 1956 w. D. SEYFRIED 2,772,212

PROCESS FOR REMOVING METALS FROM CRUDE OILS AND THEN HYDRODESULF'URIZINGTHE CRUDE OILS Filed June 30, 1954 23 35 MAKE-UP H2 1 22 RECYCLE H l2 l5l9 A a I a J 35mm roe DESULFUR/ZA TION l3 I6 uN/T 24 H20+A5H 11 01-45GASOLINE x 3/ HYDROFORMER GASOLINE 0/5 TILL/I710 ZONE IN V EN TOR.

Wilson 0. Seyfried,

ATTORNEY.

United States Patent PROCESS FOR REMOVING METALS FROM CRUDE OILS ANDTHEN HYDRODESULFURIZING THE CRUDE OILS Wilson D. Seyfried, Baytown,Tex., assignor, by mesne assignments, to Esso Research and EngineeringCompany, Elizabeth, N. J., a corporation of Delaware Application June30, 1954, Serial No. 440,436 2 Claims. (Cl. 196-28) This invention isdirected to a method for removing sulfur from crude oil and crude oilfractions having a high ash content.

The present invention is particularly adapted for the treatment of acrude oil containing materials which deposit as solids upon catalyticsurfaces when the hot feed stock is brought into contact with saidcatalytic surfaces. The nature of these materials in the crude petroleumand in the crude petroleum fractions is not completely understood. Thesematerials may be porphyrins, porphyrinmetal complexes including nickel,iron, copper, vanadium porphyrins as well as other organometalliccompounds. These also may in part consist of high boiling hydrocarbonresidues. Hereafter for convenience in the specification these materialswill be referred to as solids residues although it is to be understoodthat actually in the feed stocks these materials may not be solids butmay be in the liquefied form and may form the solids only when the feedstock is vaporized at a high temperature and brought into contact with acatalytic surface.

Specific examples of crude petroleum oils and fractions of crudepetroleum oils are West Texas crudes, Hawkins crudes, Middle Eastcrudes, and the like.

The present invention is directed to a method for hydrodesulfurizingpetroleum feed stocks which are selected from the class of high ashcontent, high sulfur content, petroleum crude oils and petroleum crudeoil fractions.

In accordance with the present invention, the feed stock to bedesulfurized is water washed in a plurality of stages to remove themetallic constituents. The washed crude oil, if it contains naphthenicacids or naphthenic acid salts, may optionally be treated with anaqueous solution of sodium naphthanates, sodium salts of sulfonic acids,sodium sulfate and sodium hydroxide. This treating step removes theacidic constituents. It is desirable to remove the naphthenic acids atthis stage of the process, for if they are not removed, additionalpickup of metals such as iron will result from reaction with pipes andvessels with which the feed stock may come in contact. As the next step,the feed stock is desulfurized by passing it in vaporized form inadmixture with hydrogen into contact with a sulfactive catalyst toreduce its sulfur content. The product from the desulfurization step maybe distilled to separate a gasoline fraction which may be hydroformedsimultaneously to upgrade the octane number and produce hydrogen whichis used in the desulfurizing step.

The method for practicing the present invention will now be described ingreater detail in conjunction with the drawing in which the sole figureis in the form of a diagrammatic flow sheet.

Turning now specifically to the drawing a feed stock which may be atotal crude petroleum oil or crude oil fraction is introduced throughline 11 into a first water washing zone A. Fresh water is introducedinto zone A through inlet line 12 and water containing ash is withdrawnthrough line 13. The feed stock from the first stage is passed throughline 14 to a second water washing stage B where it is washed with freshwater introduced ICC through line 15 and withdrawn with dissolved ashconstituents through outlet line 16. The feed stock from the secondwashing stage is passed through line 17. If this material containsappreciable amounts of naphthenic acids it is then passed to treatingstage C but alternatively if the material does not contain appreciableamounts of naphthenic acids stage C may be bypassed with the materialbypassing through line 18. In treating stage C, a fresh treating mixtureis introduced through line 19 and is withdrawn through line 20. Thematerial introduced through line 19 is a mixture made up of componentsin ranges as follows:

Water 72.5-84.5

This solution of treating reagent should have a specific gravity no lessthan 1.1. By way of specific example, a solution having the followingcomposition may be used:

Weight percent Sodium sulfonates 30 Sodium sulfate 10 Free sodiumhydroxide 1 Water 59 A more detailed description of the washing step isdescribed and claimed in copending U. S. Patent application Serial No.255,464 entitled Treatment of Acidic Oils, filed November 8, 1951, inthe name of Linnie P. Hodges.

The treated oil from step 17 or alternatively the oil from bypass line18 is discharged into line 21 and passes to drier D where entrainedwater is removed therefrom. The dried feed stock passes through line 22and is admixed in hydrogen discharged into line 22 from line 23 themixture of feed stock and hydrogen then passing to desulfurization unitE.

Desulfurization unit E contains a sulf-active catalyst. Sulf-activehydrogenation catalysts suitable for use are known to the art. Examplesof suitable catalysts selected from this class are the oxides andsulfides of V, Cr, Mn, Fe, Co, Ni, Mo, W. These may be used either aloneor in admixture or may, if desired, be used with other materials such asalumina, magnesia silica, zinc oxide. Specific examples of suitablesulf-active catalysts are cobalt molybdate, nickel tungsten sulfide,cobalt sulfide, molybdenum oxide, nickel sulfide and tin sulfide. It ispreferred that sulficient hydrogen be admixed with the feed stock tomaintain a ratio of hydrogen to oil within the range of 2 to 40 moles ofhydrogen per mol of said stock. The following conditions should bemaintained within reactor E: A temperature within the range of 700850F., a pressure in the range of 0 to 500 pounds per square inch gauge anda feed rate in the range of 0.2 to 10 volumes of liquid feed per volumeof catalyst per hour. The mixture of hydrogen and treated feed stock iswithdrawn from vessel E through line 24 and passed to a separator Fwhere hydrogen is separated from the desulfurized feed stock and thehydrogen recycled to vessel B through line 23. The treated feed stock iswithdrawn from separator F through line 24a and passed to a distillationzone G Where it is separated into a gas fraction withdrawn through line30, a gasoline fraction withdrawn through line 31, a gas oil fractionwithdrawn through line 32, a lubricating distillate withdrawn throughline 33 and a residual oil withdrawn through line 34.

The gasoline fraction passes from line 31 to a hydroformer unit H.

Hydroforming operations are well known to the art. For a descriptionsee, for example, Oil and Gas Journal,

vIarch 27, 1941, page 86'and the Jour nal'of Petroleum 'eactionsinvolvea net efiect of taking hydrogen away.

ro'rn the hydrocarbon molecules. The chemical reacions involved arecomplex and are generally considered d'ccnsist of dehydrogenationand'cyclization. Other 'eactions such'as cracking, hydrogenation, anddesulfuri- :ation may also occur.

'By way of specific example, it is preferred that the 'eaction inhydroforrner unit H take place within the ange of 900 to 950 F. Whileany reforming catalyst n general may be employed, a preferred group maybe he same type of suit-active catalyst as used in desulfnri :ation unitE and in order to simplify the description hese specific catalysts willnot be again enumerated. In iydroformer unit H there is an'over-all net,production )f hydrogen and this hydrogen is withdrawn through line 55'and is added as make-up hydrogen to the recycle hylrogen in line 23,.themixtures of make-up hydrogen and 'ecycle hydrogen being admixed with theoil charged to iesulfurizing unit E. i

.Hydroformed gasoline of improved octane number is withdrawn fromhydroformer unit H through line 36. lhus, it will be seen. that thehydroforming of the gasoine fraction in hydroforming unit H serves adual PUT: aoser The gasoline fraction produced by desulfurization mit Eis particularly suitable for upgrading in hydrot'ormer unit H so that inunit H thev quality of the gasoine fraction is substantially improvedand at the same 4 time hydrogen is produced for the desulfurization unitE.

Having fully described and illustrated the invention of the presentapplication, What I desire to claim is:

1. In a method for treating a petroleum feed stock to behydrodesulfurized in a hydrodesulfurization zone in contact with asulf-active catalyst, said feed stock being selected from the groupconsisting of crude oils and crude oil fractions containing anappreciable amount of ash formingconstituents and acid constituents,including acid constituents selected from the group consisting ofnaphthenic acids and naphthenic acid salts, the improvetaining. analkali metal hydroxide, an alkali metal salt of sulfonic acid and analkali metalsalt of an inorganic acid to remove acid constituentstherefrom.

2. A- process as in claim '1 wherein the'said aqueous solution containsabout 30 weight percent of sodium sulfonates, about 10 weight percent ofsodium sulfate, about 1 weight percent of sodium hydroxide and about 59weight percent of water.

References Cited in the file of this patent UNlTED STATES PATENTS

1. IN A METHOD FOR TREATING A PETROLEUM FEED STOCK TO BEHYDRODESULFURIZED IN A HYDRODESULFURIZATION ZONE IN CONTACT WITH ASULF-ACTIVE CATALYST, SAID FEED STOCK BEING SELECTED FROM THE GROUPCONSISTING OF CRUDE OILS AND CRUDE OIL FRACTIONS CONTAINING ANAPPRECIABLE AMOUNT OF ASH FORMING CONSTITUENTS AND ACID CONSTITUENTS,INCLUDING ACID CONSTITUETS SELECTED FROM THE GROUP CONSISTING OFNAPHTHENIC ACIDS AND NAPHTHENIC ACID SALTS, THE IMPROVEMENT WHICHCOMPRISES THE STEPS OF WATER WASHING SAID FEED STOCK IN SEQUENCE IN APLURALITY OF WATER WASHING ZONES WITH FRESH WATER IN EACH OF SAID ZONESTO REMOVE ASH FORMING CONSTITUENTS THEREFROM, AND CONTACTING SAID WATERWASHED FEED STOCK WITH AN AQUEOUS SOLUTION CONTAINING AN ALKALI METALHYDROXIDE, AN ALKALI METAL SALT OF SULFONIC ACID AND AN ALKALI METALSALT OF AN INORGANIC ACID TO REMOVE ACID CONSTITUENTS THEREFROM.